In May 2000, the U. S. National Highway Traffic Safety Administration (NHTSA) contacted Ford and Firestone about the high incidence of tire failure on Ford Explorers, Mercury Mountaineers, andMazda Navajos fitted with Firestone tires. Ford investigated and found that several models of 15-inch Firestone tires (ATX, ATX II, and Wilderness AT) had very high failure rates, especially those made at Firestone’s Decatur, Illinois plant. This was one of the leading factors to the closing of the Decatur plant. Joan Claybrook, who was the president of the public advocacy group Public Citizen and previously an Administrator of the NHTSA, stated before the Transportation Subcommittee United States Senate Committee on Appropriations on September 6, 2000, that, “ there was a documented coverup by Ford and Firestone of the 500 defect”.
Also Clarence Ditlow; Executive Director for the Centre for Auto Safety in his statement before the Senate Committee on Commerce, Science and Transportation in Washington D. C., September 20, 2000 stated “ Emerging Information shows that both Ford and Firestone had early knowledge of tread separation in Firestone Tires fitted to Ford Explorer vehicles but at no point informed the NHTSA of their findings”.  ————————————————-
Possible causes[edit source | editbeta]
The Ford Explorer was first offered for sale in March 1990. Ford internal documents show the company engineers recommended changes to the vehicle design after it rolled over in company tests prior to introduction, but other than a few minor changes, the suspension and track width were not changed. Instead, Ford, which sets the specifications for the manufacture of its tires, decided to remove air from the tires, lowering the recommended pressure to 26 psi. The maximum pressure stamped into the sidewall of the tire was 35 psi; however tires should only be inflated to the pressure listed by the vehicle’s manufacturer. The failures all involved tread separation — the tread peeling off followed often by tire disintegration. If that happened, and the vehicle was running at speed, there was a high likelihood of the vehicle leaving the road and rolling over. Many rollovers cause serious injury and even death; it has been estimated that over 250 deaths and more than 3, 000 serious injuries resulted from these failures, with not all occurring on Ford Motor Company vehicles. It is estimated that 119 of the 250 deaths resulted from a crash with a Ford Motor Company vehicle. Ford and Firestone have both blamed the other for the failures, which has led to the severing of relations between the two companies.
Firestone has claimed that they have found no faults in design nor manufacture, and that failures have been caused by Ford’s recommended tire pressure being too low and the Explorer’s design. Ford, meanwhile, point out that Goodyear tires to the same specification have a spotless safety record when installed on the Explorer, although an extra liner was included into the Goodyear design after recommendations to that effect were made to Ford. Firestone included an extra liner in its product and this was then also used to replace tires on Ford Explorers. It is well accepted within the tire manufacturing industry that use of a “ belt edge layer” or as referred above as an extra layer, virtually eliminates belt edge separation. As a rubber tire moves on the road, it generates tremendous heat.
As steel belts heat up, they expand and want to pull away or separate from rubber. The use of nylon belt edges has been in use since radial tires were first developed in the 1970s. Nylon, when heated, actually constricts in size; thus keeping the belt edge integrity. Firestone could achieve cost savings from eliminating this extra layer. Some outside observers have speculated about the blame worthiness of both parties; Firestone’s tires being prone to tread separation and failure, and the SUVs being especially prone to rolling over if a tire fails at speed compared to other vehicles.